The purpose of this work is to gain detailed MCD spectroscopic information about liver microsomal cytochromes P-450. For this purpose we have isolated several highly purified forms of rabbit liver cytochrome P-450 using procedures developed by Coon. At present the spectra of one of these forms have been used for comparison with those obtained from purely synthetic models for the reduced plus CO state, the high-spin substrate-bound state and with some hyper-porphyrins. Work involved in intercomparison of the several forms with each other as well as their binding capabilities is now in progress. BIBLIOGRAPHIC REFERENCES: Magnetic Circular Dichroism Studies of Non-Iron "Hyper" Porphyrin Complexes as Models for Reduced positive CO Cytochrome P-450. J.H. Dawson, J.R. Trudell, G. Barth, R.E. Linder, E. Bunnenberg, C. Djerassi, M. Gouterman, C.R. Connell, and P. Sayer. J. Amer. Chem. Soc., 99, 641 (1977). Structural-Vibrational Effects in Magnetic-Circular Dichroism Spectra. L. Seamans, A. Moscowitz, K. Morrill, J.S. Dixon, G. Barth, J. Amer. Chem. Soc., 99, 724 (1977).